Diagnostic Accuracy of Fasting Blood Sugar and Oral Glucose Challenge Test for Gestational Diabetes Mellitus

Fasting Blood Sugar and Oral Glucose Challenge Test for GDM

Abstract

Despite multiple studies on gestational diabetes mellitus (GDM) screening, evidence on the concurrent validity and practical use of fasting blood glucose (FBS) and glucose challenge test (GCT) remains limited. Objectives: To compare the diagnostic accuracy of FBS, and oral GCT in detecting GDM, taking oral glucose tolerance test (OGTT) as the gold standard. Methods: This cross-sectional study was conducted at the Department of Obstetrics and Gynecology, Shahida Islam Teaching Hospital, Lodhran, Pakistan, from March to December 2023. A total of 160 pregnant women aged 20–40 years (gestation>20 weeks) were included. Diagnostic performance of FBS and GCT was assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy. IBM-SPSS Statistics, version 26.0, was used for data analysis. McNemar’s test was applied to these how FBS, or GCT, agreed with GTT in diagnosing GDM, taking p<0.05 as significant. Results: The mean age and gestational age were 29.54 ± 5.35 years and 27.81 ± 2.48 weeks, respectively. The sensitivity of FBS in the diagnosis of GDM was 78.3%, and that of GCT was 84.2% (p=0.700). The specificity of FBS and GCT was 86.8% and 96.9%, respectively. The PPV of FBS was 81.8%, and that of GCT was 85.7%. The NPV of FBS and GCT were 84.0% and 91.8%, respectively (p=0.994). Accuracy of FBS was 83.1%, and GCT was 89.4%. Conclusions: It was concluded that the diagnostic accuracy of FBG and GCT in diagnosing GDM is high, with GCT demonstrating superior effectiveness. OGTT remains the definitive gold standard for confirming GDM.